Tarjan with very large graph generate "goroutine stack exceeds 1000000000-byte limit"

[thomaspeugeot]

Situation:
I have a graph with close to 2 Millions nodes and many more edges

Problem:
call to Tarjan provokes a stack limit error

Note:
goraph is great piece of SW and this is a minor issue. A work around was found.

row  1726 4030 MiBGraph nb of nodes                1992378
runtime: goroutine stack exceeds 1000000000-byte limit
fatal error: stack overflow

runtime stack:
runtime.throw(0x551515, 0xe)
        C:/Go/src/runtime/panic.go:608 +0x79
runtime.newstack()
        C:/Go/src/runtime/stack.go:1008 +0x737
runtime.morestack()
        C:/Go/src/runtime/asm_amd64.s:429 +0x97

goroutine 1 [running]:
runtime.interhash(0xc0f0001450, 0xe8426d0d, 0x42a209)
        C:/Go/src/runtime/alg.go:140 +0x182 fp=0xc0f0001368 sp=0xc0f0001360 pc=0x402f92
runtime.mapaccess2(0x524820, 0xc0271566f0, 0xc0f0001450, 0x3011f, 0x0)
        C:/Go/src/runtime/map.go:456 +0x78 fp=0xc0f00013b0 sp=0xc0f0001368 pc=0x40d038
github.com/gyuho/goraph.(*graph).unsafeExistID(...)
        C:/Users/Tensor/go/src/github.com/gyuho/goraph/graph.go:220
github.com/gyuho/goraph.(*graph).GetTargets(0xc027156780, 0x571f00, 0xc01d2b91a0, 0x0, 0x0, 0x0)
        C:/Users/Tensor/go/src/github.com/gyuho/goraph/graph.go:389 +0xde fp=0xc0f00014d0 sp=0xc0f00013b0 pc=0x4fc4ae
github.com/gyuho/goraph.tarjan(0x573200, 0xc027156780, 0x571f00, 0xc01d2b91a0, 0xc00009c0c0)
        C:/Users/Tensor/go/src/github.com/gyuho/goraph/strongly_connected_components.go:138 +0x1fe fp=0xc0f00016d0 sp=0xc0f00014d0 pc=0x4fd00e
github.com/gyuho/goraph.tarjan(0x573200, 0xc027156780, 0x571f00, 0xc01d2b9220, 0xc00009c0c0)
        C:/Users/Tensor/go/src/github.com/gyuho/goraph/strongly_connected_components.go:148 +0x4a3 fp=0xc0f00018d0 sp=0xc0f00016d0 pc=0x4fd2b3
github.com/gyuho/goraph.tarjan(0x573200, 0xc027156780, 0x571f00, 0xc01d2b92e0, 0xc00009c0c0)
        C:/Users/Tensor/go/src/github.com/gyuho/goraph/strongly_connected_components.go:148 +0x4a3 fp=0xc0f0001ad0 sp=0xc0f00018d0 pc=0x4fd2b3
github.com/gyuho/goraph.tarjan(0x573200, 0xc027156780, 0x571f00, 0xc04810c6e0, 0xc00009c0c0)